Sennheiser M3AEBTXL Instruction Manual page 17

If you connect the analog audio cable to the headphones, the
flight mode is also activated (Bluetooth wireless connection is
off) (> 27).
Switching the headphones off
▷
Fold the left ear cup and then the right ear cup inwards over a slight resistance of the joint.
You hear the voice prompt "Power off" and the LED flashes red 3 times. The headphones switch off.
When you remove the headphones and place them on your
shoulders, the headphones switch to standby mode to save
power. When you put the headphones on again, the standby
mode is deactivated.
When the headphones are switched off, keep a minimum dis-
tance of 10 cm between the headphones and strong magnets,
as the headphones may switch on unintentionally.
Putting the headphones on and adjusting the headband
17